![]() Use of IN and NOT IN keywords in Subqueriesįind the names of employees who are working on a project.Ĭode: Select e_name from employee where e_id IN(Select distinct e_id from project) The above query will eliminate all records that have the employee’s address, either delhi, banglore, or Noida, and prints all records other than these three whose address is delhi, banglore, or noida. The above query will select all records from the table employee where the employee’s address is either delhi, banglore, or Noida.Ĭode: Select * from employee where address NOT IN('delhi','banglore','noida') To find the detail of an employee whose address is either delhi, banglore, or Noida.Ĭode: Select * from employee where address IN('delhi','banglore','noida') Insert into project values(4,105, 'wallet', 'gurgoan') Insert into project values(4,104,'oauth','chennai') Insert into project values(3,103,'payments','delhi') Insert into project values(5,102,'c++','lucknow') ![]() Insert into project values(1,101,'java','chennai') Insert into employee values(6,'rahul','noida') Ĭode: create table project(e_id int not null,p_id int primary key,e_name varchar(150),Address varchar(150)) Insert into employee values(5,'ajay','hyderabad') ![]() Insert into employee values(4,'sonika','chennai') Insert into employee values(3,'somya','banglore') Insert into employee values(2,'aman','lucknow') Insert into employee values(1,'ashish','delhi') To explain MySQL IN and NOT IN functions, we will take another table named employee and project.Ĭode: create table employee(e_id int primary key,e_name varchar(150),Address varchar(150)) MySQL IN functions and NOT In function both works with multiple column strategy. The above query will select all rows from table students where the roll_no of students is not either 1 or 2. The NOT IN will eliminate all the records that match the values passed in the function and selects all the records that are not present in the values of the function.īelow is the query of mysql NOT IN with where clause:Ĭode: Select * from students where roll_no NOT IN (1, 2) Since the IN clause will select all the records that contain or match the values passed in the IN function. NOT IN keyword works simply opposite to IN clause. The above query will select all records from table students where the roll_no of students is either 1 or 2, or 3. Insert into students values (3,'divya','Arch') īelow is the query of the mysql IN function with the where clause, which selects only the rows or records whose values match the values passed in the mysql IN function as arguments.Ĭode: Select * from students where roll_no IN (1, 2, 3) Insert into students values (2,'rahul','C++') Once the table is created, we can now insert values into it.īelow is the query for the insert statement:Ĭode: Insert into students values (1,'ashish','java') Mysql> select count(*) from TABLE_A where NOT EXISTS (select * FROM TABLE_B WHERE TABLE_B.Fkey = TABLE_A.Code: create table students (roll_no int, student_name varchar (150), course varchar (150)) Īfter creating the table, students, now it’s time to insert values into the table. Mysql> select count(*) from TABLE_A left join TABLE_B on TABLE_A.Pkey = TABLE_B.Fkey where TABLE_B.Pkey is null Mysql> select count(*) from TABLE_A where TABLE_A.Pkey not in (select distinct TABLE_B.Fkey from TABLE_B ) ![]() | version_comment | MySQL Community Server (GPL) | Unfortunately it seems to be a issue with MySql usage of "NOT IN" clause, the screen-shoot below shows the sub-query option returning wrong results: mysql> show variables like '%version%' That’s why the best way to search for missing values in MySQL is using a LEFT JOIN / IS NULL or NOT IN rather than NOT EXISTS. The code that executes EXISTS predicate is about 30% less efficient However, these three methods generate three different plans which are executed by three different pieces of code. MySQL can optimize all three methods to do a sort of NESTED LOOPS ANTI JOIN. Since there are three pieces of code in MySQL that essentialy do one job, it is possible that the code responsible for EXISTS makes some kind of an extra check which takes extra time. It’s hard to tell exact reason for, since this drop is linear and does not seem to depend on data distribution, number of values in both tables etc., as long as both fields are indexed. The algorithms are in fact the same in fact and the queries complete in same time. Since MySQL is not capable of using HASH and MERGE join algorithms, the only ANTI JOIN it is capable of is the NESTED LOOPS ANTI JOINĮssentially, is exactly the same plan that LEFT JOIN / IS NULL uses, despite the fact these plans are executed by the different branches of code and they look different in the results of EXPLAIN. MySQL, as well as all other systems except SQL Server, is able to optimize LEFT JOIN / IS NULL to return FALSE as soon the matching value is found, and it is the only system that cared to document this behavior.
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